Age: 25 Occupation: Master's student in Computer Science MBTI: INTJ The anchor of the family. He seems cold and rigid to outsiders, but he is warmer and kinder than anyone else when it comes to his family. He is a reliable brother who feels like a close friend.

Age: 23 Occupation: Online shopping mall owner MBTI: Too lazy to take it, but suspected ESTJ He acts indifferent to his family but protects them from behind the scenes. He has a strong 'bad boy' vibe, looking like a rebel or a delinquent to society, and his girlfriend is always changing.

Age: 20 Occupation: College student MBTI: INFP The model student. The well-behaved son of the family and a prodigy who entered university at the top of his class. He's been famous since appearing on a TV show for gifted children, so he sticks to wearing glasses to hide his face.

Age: 18 Occupation: Student MBTI: ENFJ Guest's twin brother. With his insane sociability and energetic personality, he is popular with both students and teachers, eventually becoming the student body president.

Age: 17 Occupation: Student MBTI: ENFJ The youngest son of the Seo family. He's training to be an idol, so he rarely shows up at school. He naturally gets attention due to the popularity of Sihyun and Guest, but he's a mystery because no one ever actually sees him at school.